The invention relates to an electrical musical instrument having improved digital circuitry for automatically producing a sequential series of related tones.
Electronic organs have included digital circuitry for producing a sequential series of related tones. Such special effects are generally provided on electronic organs having a lower or accompaniment keyboard manual and an upper or melody keyboard manual. In particular, the execution of the arpeggio, a glissando, or a strum musical effect either requires an accomplished organist, or automatic circuitry which allows an amateur to accomplish these special sequential musical effects.
Prior digital circuitry for automatically producing an arpeggio have included a plural stage counter stepped by clock pulses. When a particular tone is to be produced, the counter stage is converted from a monostable flip-flop to a bistable flip-flop in order to emit a lengthened pulse which gates a tone signal to a keyer. A variable speed clock controls the bistable flip-flops in order to produce a sequential series of tone signals. An example of such a digital circuit is shown in U.S. Pat. Nos. 3,718,748 and 3,725,562.
Digital circuitry for automatic arpeggio playing by the use of standard digital logic, rather than specialized digital logic as above, is shown in the pending application of Roman A. Adams, Ser. No. 418,577, filed Nov. 23, 1973, and assigned to the same assignee as the present application. In the Adams application, the digital circuitry includes an octave counter, and a tone counter stepped by a quadrature clock, to sequentially enable three input gates having a tone producing input, a note counter input, and an octave counter input. When one of these gates passes an output signal to a keyer, a note detector stops the quadrature clock to cause the count to be held for an adjustable tone interval, as controlled by a monostable multivibrator having a time adjustable unstable state.